The present invention relates to a replaceable cartridge for an air drier, the air drier comprising a base member with means for supplying and carrying away air to and from, respectively, a cylindrical dome-shaped container, releasably attached to the base member and containing the cartridge for desiccant, which is divided by a cylindrical dividing wall into a central compartment containing desiccant and an outer annular compartment.
Air driers of this type are known in the art. In many cases it is desired to obtain a long flow path for the air to be dried through the desiccant, at the same time as the total volume of the cartridge shall be utilized for desiccant, so that the capacity is as great as possible. For such cases a winding path or labyrinth for the air can be provided. In other cases it may be desired to have a combination of filter material and desiccant in the cartridge; the filter material has the purpose of removing other matters, such as dirt particles, hydrocarbons and oil, that can be detrimental to the desiccant, the only purpose of which is to catch water molecules.
It is also a desire to obtain a versatile cartridge, which can be used for different purposes and combinations of desiccants and filters, for obtaining advantages with regard to manufacturing and storing.
Further, the design shall allow the greatest possible air flow and temperature.
The objects mentioned above are fulfilled and problems with prior designs are removed if according to the invention the cartridge is provided at its top end with means for allowing air communication inside the container between the two compartments and at its bottom end with means for allowing supply of air to either of the compartments and removal of air from the other of the compartments.
Normally, the air to be treated is supplied first through the outer compartment and then to the central compartment through said holes or passages in the cartridge top wall, but the opposite flow direction is also possible. The design is such that the two compartments are physically separated but are in pneumatical contact (at least when the cartridge is mounted in its container). The two compartments have to be separately filled with suitable contents. The central compartment always contains desiccant, whereas there is full freedom to choose contents in the outer compartment depending on the purpose of the air drier. The outer compartment thus can be completely filled with desiccant, if a maximum drying capacity is needed. In other cases the outer compartment can for example contain a filter together with desiccant or only a filter.
The outer compartment can even be left without any content. In that case the flow direction may be reversed, and the outer compartment can be used as a regeneration container for dried air.
The physical separation of the two compartments means that they have to be filled separately (with for example desiccant and filters in different combinations). The useful life of the relatively sensitive desiccant can hereby be increased, and furthermore the desiccant can be protected against harmful influence of oil, particles and hydrocarbons.